$\text{CPT}$ and strings

Abstract

We define the string space-time symmetries $\text{C,P,T}$ and their products. The effects of nonlocal interactions and the infinite number of particle fields are incorporated using string field theory. At the dynamical level, $\text{C,P,T}$ and their products are preserved by the open bosonic string. Only the product $\text{CPT}$ is dynamically preserved by the superstring, although a modified action can be constructed to preserve $\text{C}$. We show that these discrete symmetries may be spontaneously broken in a natural way by string interactions. In a favorable scenario, this might lead to $\text{CPT}$ violation in the K-K̄ system just below the limits of present experiments.